So I know the catch is that only one device can use the tx and rx lines. I have two devices that require serial tx/rx communication. Is there a way around this problem? I was thinking a switch that can be switched on/off with one of the other digital pins? Thoughts? Thanks in advance.

Well, the Uno can Tx to both at same time.Need a way to only Rx from one at a time.What voltage levels are being used? TTL? RS232? RS485?With TTL, you could use a pin as you suggested to enable one Rx line or the other thru their own 74HC125 buffer.http://www.digikey.com/product-detail/en/74HC125N,652/568-1393-5-ND/762997